Beverages, such as carbonated soft drinks, form a foam head when poured into a cup due to the rapid release of the carbonation during pouring from a can, dispenser, or the like. The low surface tension of plastic and waxed cups offer many nucleation sites to further contribute to foaming. When a foam head is formed, the server must wait 10 to 15 seconds for the head to collapse before adding to the cup until it is full. Alternatively, the server may pour at an extremely slow rate to minimize agitation and formation of a foam head, in which case a comparable time is required to completely fill the cup without overflowing the same. Of many carbonated beverages, those containing the artificial sweetener aspartame produce the most foaming and most persistent foam. Root beer, with or without aspartame, is also persistent in foam.
Many businesses are faced with the problem of rapidly serving a large number of drinks in disposable cups over limited time periods, which problem is exacerbated by the waiting time required for the foam head to dissipate before the cup may be filled. For example only, substantially all domestic scheduled airlines serve complementary soft drinks in disposable, single-use plastic or paper cups. Generally, flight attendants add ice to the empty cup and pour a room-temperature carbonated beverage over the ice in order to cool the beverage. Carbonation released during pouring results in a persistent foam head that occupies on the order of 20 to 25% of the volume of the cup. Passengers expect a full cup of beverage, and so the flight attendant must wait until the foam head collapses and then add to the cup until it is full. This wastes the time of the attendants which especially on short flights and/or full flights is very limited. To speed up service, the attendant sometimes gives the passenger the cup and entire can without filling the cup, or after partially filling the same. Although this is an effective solution to the wasted time problem it is more expensive to the airline since one can usually fills three cups. Airlines have also tried stocking smaller cans of carbonated beverages, such as the 5.5 ounce size commonly used on overseas flights, but domestic passengers often complain because they feel cheated by the small portion. Other businesses such as movies, sporting events, fast food chains and other restaurants and convenience stores where rapid serving of carbonated beverages in disposable cups is practiced are faced by the same problems in filling of the cups.
The prior art includes many designs of disposable or single use cups that have been modified to hold a single serving of a powder which, when mixed with water or carbonated water at the time of use, dissolves to make a beverage of the concentration needed to fill the cup. Examples of such designs include U.S. Pat. Nos. 3,915,296, to Spencer; 4,096,947, to Morse; 3,407,922, to Palmer and 3,526,316, to Kalogris. Also, the use of an antifoaming agent as part of dry beverage powder formulations that produce various flavors and carbonation when plain water is added is known in the prior art. Examples include U.S. Pat. Nos. 3,983,251, to Singh; 2,953,459, to Diller; and 4,343,819, to Wood.